This article focuses on the ethics of doing ethnographic research within a vulnerable population, specifically homeless women. In this article I reflect on a number of ethical dilemmas that occurred during the fieldwork related to exclusion criteria, recruitment process, informed consent, the participant-researcher relationship and the researcher's safety. Through self-reflection I explore how applying ethical principles to researching a vulnerable population raises difficult questions. The aim of this article is to encourage further debate about the application of ethical principles when researching a vulnerable population.